Process for producing a stick of adhesive

ABSTRACT

A process for producing a stick of adhesive, having a rotatable base part with rotary spindle, which spindle is engaged in a holding element for the stick material (plunger, small basket, anchoring disc), which holding element is fitted into a sleeve surrounding the stick material. The rotary spindle, provides controlling movement of the stick-shaped adhesive material either up or down. The sleeve (2) together with the plunger (1) is formed in a one-part injection molding which is joined, via predetermined breaking points (3), to the sleeve wall. For the assembly, the base part, with rotary spindle is pushed through a centered recess in the plunger until the lower periphery of the sleeve comes to rest against the upper part of the base part. The adhesive stick material is then poured into the unit thus formed (sleeve, plunger and base part with rotary spindle), and, after the filling operation is complete, the rotatable base part is actuated and, as a result, the plunger is lifted into the intended end position (10), with tearing off of the predetermined breaking points. The structural arrangement for carrying out the process, consists of: a) a rotatable base part (7), a rotary element (7B) and a rotary spindle (7A), the base part having two support plates (9A, 9B), and b) a one-part injection molding, comprising a sleeve part (2) which is open at both ends and a plunger (1) with predetermined breaking points (3).

FIELD OF THE INVENTION

This invention relates to the production of sticks of adhesive, having arotatable base part with rotary spindle which engages in a holdingelement for the stick material, which holding element is, for example,in the form of an anchoring plate, a plunger or a small basket. Theinvention particularly relates to holding elements which are firmlyfitted into an outer sleeve which protects the stick material againstdrying out and against damage.

BACKGROUND OF THE INVENTION

In the production of the aforementioned adhesive sticks, difficultieshave arisen with the rapid assembly of the adhesive stick structuresbefore the filling with the adhesive material in the stick form.

The outer sleeve, the holding element and the base part with rotaryspindle are produced separately and then assembled. During assembly, therotary spindle must be rapidly and very accurately rotated by means of acentral recess in the holding element which was previously inserted intothe outer sleeve, while the lower edge of the outer sleeve is made tosimultaneously engage the base part.

Considerable forces are produced at this stage, which results insignificant amounts of rejected product caused by damaged holdingelements and damaged rotary spindles. Aside from economic loss stemmingfrom the rejected product, there is additional cost entailed with theneed for recycling of reject materials.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to reduce oreliminate damage during assembly with enhanced efficiency of productionand economic savings thereby.

In accordance with the present invention, the outer sleeve and theholding element, are configured in the form of a plunger, in a one-partinjection molding, with the plunger being firmly joined to the sleevewall via predetermined breaking points.

As a result, only two assembly parts have to be combined with oneanother, namely the one-part injection molding with the plunger therein(arranged so as to be centered and whereby it cannot be tilted); and thebase part with the rotary or threaded spindle.

In accordance with the present invention a stick of adhesive is producedwith a rotatable plunger having a rotary spindle and a base part firmlyjoined thereto and which spindle supports the stick material. Thespindle and stick material are in turn contained in a sleeve which isclosed with a closure cap.

The sleeve and plunger are formed as a one-part injection molding, withthe plunger being joined to the sleeve wall via predetermined breakingpoints. The base part, with rotary spindle, is adapted to be pushedthrough a recess, arranged so as to be centered, in the plunger untilthe lower sleeve periphery comes to rest against the upper part of thebase part. The stick material is then poured into the unit thus formed,which comprises sleeve and base part with rotary spindle. After thefilling operation is complete, the rotatable base part is actuated and,as a result, the plunger is lifted into the intended end position bymeans of the rotary spindle, with tearing off of the predeterminedbreaking points. The support plate of the plunger is pushed, by means ofperipheral notches or grooves provided on it, onto guide webs providedon the inside of the sleeve wall, whereupon the closure cap is placed onthe sleeve filled with adhesive.

The injection molding which forms the sleeve with plunger may veryexpediently be made of polypropylene.

Since the base part with the rotary spindle may be made of the sameplastic as the sleeve or of a plastic compatible therewith, with thepiston being firmly anchored in the sleeve and the rotation of therotary spindle able to be carried out without damaging the sealingelements (such as the sealing lip of the spindle and sealing surface ofthe sleeve) there are several significant advantages. Not only is theassembly simplified as a result of the present invention, but thedisposal of waste and reject material is also facilitated.

The invention also relates to an arrangement for carrying out theprocess described above, which arrangement is explained in greaterdetail with reference to the accompanying drawing, in which:

SHORT DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a longitudinal section through a stick of adhesive beforeit is filled with stick material and

FIG. 2 shows a top view in the center of the plunger.

DETAILED DESCRIPTION OF THE DRAWING AND THE PREFERRED EMBODIMENTS

The arrangement according to the invention consists of:

(a) a rotatable base part (7) which is firmly joined, via a rotaryelement (7B), to a rotary spindle (7A), and having support plates (9A,9B) which correspond to the clear diameter of the sleeve (2). Thesupport plates (9A, 9B) are arranged at a distance from one another,(the support plate of the plunger and support plate of the rotaryspindle respectively); and

(b) a sleeve part (2), open at both ends, and having a plunger (1) whichis firmly joined therein via predetermined breaking points (3). Theplunger (1) has anchoring elements and support elements for the stickmaterial, and is provided with a centrally located recess. The plunger(1) further has support vanes (11) on the outer periphery thereof,whereas guide webs (12) are provided on the inner wall of the sleevepart (2), extending in the longitudinal direction.

The plunger (1) is preferably designed in the form of a small basketwhich has on its inner wall threaded lugs (5A) and preferably also hasthreaded lugs (5B) on the outer wall of the central recess.

According to a further preferred embodiment of the invention, therecess, arranged so as to be centered, in the plunger (1) is formed fromat least two elastic tongues (6) which are opposite one another andwhich simultaneously effect the engagement with rotary spindle (7A).

When the elements are in the adhesive filling position, at least one airchannel (4) is expediently present between the inner wall of the sleeveand the part (7, 7A, 7B). After the part (7, 7A, 7B) has reached the endposition (10), the air channel (4) is no longer connected to the spacefilled with the adhesive stick material.

Area (8) in FIG. 1 represents the engagement mechanism between the lowerend of the sleeve (2) and the base part (7), which, when effected,results in a complete unit being formed which is ready to receive theadhesive stick material.

The support vanes (11) on the plunger periphery prevent a tiltingmovement of the plunger during rotating in of the rotary spindle, withthe elastic tongues (6) further facilitating the rotating-in operation.The plunger (1) may of course also be designed in another way, forexample as a plate with an anchoring disc arranged thereon or as a nut,only with threaded lugs on the inner wall. It is only necessary to takecare that the stick material being filled in, can be readily rotatedforwards and back again, together with the plunger, after it has set,without remaining adhered to the inner wall of the sleeve, that is tosay the adhesive force of rest has to be overcome.

When the plunger is designed as a plate, with anchoring elements, theplate has to have a recess and an empty space disposed therebelow sothat the stick material extends as far as the upper support plate and,as a consequence, itself contributes to the anchoring.

I claim:
 1. A process for producing an adhesive stick comprising arotatable base part with a rotary spindle, which is firmly joinedthereto; a plunger for supporting an adhesive stick material, with saidplunger having a centrally located recess; a sleeve surrounding theadhesive stick material; and a closure cap, said process comprising thesteps of:a) forming the sleeve and plunger together with a one-partinjection molding, wherein the plunger is joined to a wall of the sleevevia predetermined breaking points, provided between the plunger and thesleeve wall; b) bringing the base part together with the plunger wherebythe rotary spindle of the base part is pushed through the recess in theplunger until a lower sleeve periphery of the plunger comes to restagainst an upper part of the base part, whereby an adhesive retainingmember is formed; c) pouring the adhesive stick material into theretaining member; d) actuating the rotatable base part, after filling ofsaid retaining member with adhesive, whereby the plunger is lifted bysupport plate means on the rotary spindle into an intended end position,thereby breaking the predetermined breaking points; and wherein supportplate means on the plunger is pushed, via peripheral notches or grooveson the plunger, onto guide webs provided on the inside of the sleevewall; and e) placing the closure cap on the upper open end of theretaining member filled with adhesive.